plot points greater than a value

clear all; clc;

%% parte dedicata a lettura dati
ncfile='T32TQM_20150704_20181230_S2_L3A_10m_TSM_CTWORCC_clip.nc'; 
ncinfo(ncfile); 
ncdisp(ncfile);
x=ncread(ncfile,'x'); 
y=ncread(ncfile,'y'); 

% import time dimension
% convert date from days since 1970-01-01 to Matlab datetime
time= ncread(ncfile,'time');

date_matlab = datetime(time, 'convertfrom','posixtime'); 

figure
for t=131
    
  startLoc = [1 1 t];
  count  = [Inf Inf 1];
  d = ncread(ncfile,'TSM',startLoc,count);
  d=d';
  
   
  vmax(t)=max(max(d));
  vmax=  vmax'
  
  B = rmmissing(d);
  vmed=mean(mean(B));
  
  [max_val,pos_idx]=max(d(:));
  [rigas,clonax]=ind2sub(size(d),pos_idx);
  [riga,colonna]=ind2sub(size(d),pos_idx);
  
  vall=max(d(:))-10;
  vall2=max(d(:))-15;

max=vall;
for i=1:length(d)
if max<vall && max>vall2
max=vall
end
end
% rob=log10(d);
  [max_val2,pos_idx2]=find(d==max);
  [rigas2,clonax2]=ind2sub(size(d),pos_idx2)
         


  clf
  mymap=pcolor(x,y,d);
  mymap.EdgeAlpha=0
  
hold on  
load coast
xx=x(riga)
yy=y(colonna)
xxx=x(4360);
yyy=y(3438);
xxxx=x(rigas2);
yyyy=y(clonax2);

plot(long,lat+0.1,'black')
scatter(xxx,yyy,'filled')
scatter(xxxx,yyyy,'filled')
scatter(xx,yy,'filled')
%contourf(x,y,d,7,'ShowText','on')
set(gca,'ColorScale','log')
caxis([1 10])
sr=colorbar
sr.Label.String = 'g/m^3';


xlabel('m');
ylabel('m')

caption = sprintf('%s','tsm [g/m3]' , date_matlab(t),'[UTC]',' V MAX_ ', vmax(t), ' v med_ ', vmed);
caption1 = sprintf('%s', date_matlab(t));

title(caption, 'FontSize', 10, 'FontWeight', 'bold', 'Color', 'b');
 pause(2)
 print(['TSM_01s'  datestr(date_matlab(t),'ddmmyyyy') '.png'],'-dpng');

xx
yy;
foce=d(4360,3438);
PTOMAX=d(riga,colonna);
dist=(((xx-xxx)^2+(yy-yyy)^2)^(1/2))/1000



end


%%%%%%%%%%%%%QUESTION%%%%%%%%%%

Hi all, I have find the maximum value and plotted it as a point with SCATTER.

I would like to find all the points> 130 containing in the matrix d, find their x and y coordinates and plot them all together.

[Walter Roberson]

max=vall;

Don't do that! As soon as you do that, you cannot use max() as a function, which is something you do call upon!

Answer 1

[Walter Roberson]

mask = d > 130;
selected_d = d(mask);
selected_x = x(mask);
selected_y = y(mask);
pointsize = 20;
scatter(selected_x, selected_y, pointsize, selected_d);  %color by d value

[DUMITRU ROBERT GUGIU]

the response to the code is as follows:

also I create a logical d=5000x5000 matrix

The logical indices contain a true value outside of the array bounds.

Error in impdati01SATELLITARE_rev4 (line 54)

selected_x = x(mask);

[DUMITRU ROBERT GUGIU]

the matrix d contains NaN elements

[Walter Roberson]

[rigas3,clonax3] = find(d > 130);
xxxxxx = x(rigas3);
yyyyyy = y(clonax3);
scatter(xxxxxx, yyyyyy, 'filled')

[DUMITRU ROBERT GUGIU]

that's the answer, it doesn't work ....

xxxxxx =

0×1 empty double column vector

yyyyyy =

0×1 empty double column vector

[Image Analyst]

You should be able to do

nanMask = isnan(d);
figure;
imshow(nanMask);
mask = d > 130;
mask(nanMask) = false;
figure
imshow(mask, []);

If you have trouble try again to remember to attach 'T32TQM_20150704_20181230_S2_L3A_10m_TSM_CTWORCC_clip.nc'

[DUMITRU ROBERT GUGIU]

hello thank you for the help.

with your advice I get a type 3 image(b&w), but I have to get a type 4 image (color).

I can't load the.nc file because it's too big.

practically, I have to see all points d> 130, save their coordinates and plot them on the color image of type 4

[DUMITRU ROBERT GUGIU]

[DUMITRU ROBERT GUGIU]

my code:

clear all; clc;

%% parte dedicata a lettura dati

ncfile='T32TQM_20150704_20181230_S2_L3A_10m_TSM_CTWORCC_clip.nc';

ncinfo(ncfile);

ncdisp(ncfile);

x=ncread(ncfile,'x');

y=ncread(ncfile,'y');

time= ncread(ncfile,'time');

date_matlab = datetime(time, 'convertfrom','posixtime');

figure

for t=233

startLoc = [1 1 t];

count = [Inf Inf 1];

d = ncread(ncfile,'TSM',startLoc,count);

d=d';

vmax(t)=max(max(d));

vmax= vmax'

B = rmmissing(d);

vmed=mean(mean(B));

[max_val,pos_idx]=max(d(:));

[riga,colonna]=ind2sub(size(d),pos_idx);

vall=max(d(:))-0.2;

vall2=max(d(:))-0.15;

max=vall;

% nanMask = isnan(d);

% imshow(nanMask);

% mask = d > 2;

% mask(nanMask) = false;

% figure

% imshow(mask, []);

clf

mymap=pcolor(x,y,d);

mymap.EdgeAlpha=0

hold on

load coast

xx=x(riga)

yy=y(colonna)

xxx=x(4360);

yyy=y(3438);

plot(long,lat+0.1,'black')

scatter(xxx,yyy,'filled')

% scatter(xxxx,yyyy,'filled')

scatter(xx,yy,'filled')

%contourf(x,y,d,7,'ShowText','on')

set(gca,'ColorScale','log')

caxis([1 5])

sr=colorbar

sr.Label.String = 'g/m^3';

xlabel('m');

ylabel('m')

caption = sprintf('%s','tsm [g/m3]' , date_matlab(t),'[UTC]',' V MAX_ ', vmax(t), ' v med_ ', vmed);

caption1 = sprintf('%s', date_matlab(t));

title(caption, 'FontSize', 10, 'FontWeight', 'bold', 'Color', 'b');

pause(2)

%print(['TSM_01s' datestr(date_matlab(t),'ddmmyyyy') '.png'],'-dpng');

% % % % %print(['imm_satellit_01S ' num2str(time(t)) '.png'],'-dpng');

xx

yy;

foce=d(4360,3438);

PTOMAX=d(riga,colonna);

dist=(((xx-xxx)^2+(yy-yyy)^2)^(1/2))/1000

end